In order to transmit data by radio, modulations, for instance the amplitude modulation, the frequency modulation or the phase modulation, of a carrier signal are generally carried out. A suitable method is to be selected for each modulation. The individual methods are mostly comparatively complicated to realize in the hardware and an integration of this hardware into digital electronic modules such as ASICs, FPGAs, CPLDs and suchlike is barely possible.
Previous modulators generally operate according to FIG. 1 with voltage-controlled oscillators and a number of simultaneously available phase branches. In the example in FIG. 1, an input signal φ(t) of the phase modulator is fed into two sub branches. The cosine part and the sine part of the signal are determined in the first and second branch respectively. The two parts are moved in the respective branch with a desired phase ΩTrt. They are then combined in an adder to form the phase-modulated signal PM. A digital phase modulator of this type is described in the publication EP 0 551 573 A2.
Furthermore, a digital phase modulator is likewise known from the patent application U.S. Pat. No. 4,206,423 A, in which all phases are generated. Two phases are especially generated with separate clock modules. The phase that is needed is selected with the aid of a phase selector logic. During the realization of such a phase modulator, many lines for signals of different phases of the same frequency are to be run. The results are correspondingly high interferences.
Wireless communication is also being used increasingly in hearing devices. Particularly in the case of transmitting digital signals, phase modulation can also be advantageous here. As hearing devices are however generally designed to be structurally very small, the lines lie correspondingly close to one another such that with conventional phase modulation methods, more interferences result.
Hearing devices are portable hearing apparatuses which are used to supply the hard-of-hearing. To accommodate the numerous individual requirements, different configurations of hearing devices such as behind-the-ear hearing devices (BTE), in-the-ear hearing devices (ITE), e.g. including concha hearing devices or completely-in-the-channel hearing devices (CIC), are provided. The hearing devices designed by way of example are worn on the outer ear or in the auditory canal. Furthermore, bone conduction hearing aids, implantable or vibrotactile hearing aids are also available on the market. In such cases the damaged hearing is stimulated either mechanically or electrically.
Essential components of the hearing devices include in principle an input converter, an amplifier and an output converter. The input converter is generally a receiving transducer, e.g. a microphone and/or an electromagnetic receiver, e.g. an induction coil. The output converter is mostly realized as an electroacoustic converter, e.g. a miniature loudspeaker, or as an electromechanical converter, e.g. a bone conduction receiver. The amplifier is usually integrated into a signal processing unit. This basic configuration is shown in the example in FIG. 1 of a behind-the-ear hearing device. One or a number of microphones 2 for recording the ambient sound are incorporated in a hearing device housing 1 to be worn behind the ear. A signal processing unit 3, which is similarly integrated into the hearing device housing 1, processes the microphone signals and amplifies them. The output signal of the signal processing unit 3 is transmitted to a loudspeaker and/or receiver 4, which outputs an acoustic signal. The sound is optionally transmitted to the ear drum of the device wearer via a sound tube, which is fixed with an otoplastic in the auditory canal. The power supply of the hearing device and in particular of the signal processing unit 3 is provided by a battery 5 which is likewise integrated into the hearing device housing 1.